Liquid fuel ignition apparatus

ABSTRACT

A liquid fuel ignition apparatus having a liquid fuel reservoir, means including a wick, an air pump and a porous filter for turning a portion of liquid fuel into bubbles, and a high voltage generator for applying a high voltage across a pair of discharge electrodes disposed in close proximity to the bubbling portion of the liquid fuel so as to ignite the liquid fuel bubbles by spark discharge occurring across the discharge electrodes.

United States atent [a] Mifune et al.

[ 1 Sept. 18, 1973 LIQUID FUEL IGNITION APPARATUS Inventors: Hideo Mifune, Hirakata; Akira Ishii;

Masanori Yokoynma, both of Kita-Kawachi-gun; Toshihiro Yamazoe, Nada-k0, Kobe, all of Japan Assignee:

Matsushita Electric Industrial (30.,

Ltd., Osaka, Japan Filed:

' May '24, 1971 Appl. No.: 146,417

Foreign Application Priority Data Ma 27, 1970 May 27, 1970 Ma 27, 1970 May'27, 1970 May 29, 1970 May 29, 1970.

May 29, 1970 US. Cl.

Int. Cl.

Japan 45/45935 Japan 45/45936 Japan 45/45937 Japan 45/45938 Japan.... 45745934 Japan.... 45/46735 Japan 45/46736 Japan,.... 45/46737 [58] Field of Search 431/264, 255, 300, 431/302; 239/552, 553.3

References Cited UNITED STATES PATENTS 3,622,258 11/1971 Guto 431/255 1,063,412 6/1913 'Buckmanm. 239/552 X 446,400 2/1891 .Wright 431/300 388,609 8/1888 Yanez 431/302 X Primary Examiner-Edward G. Favors Attorney-Stevens, Davis, Miller & Mosher [57] ABSTRACT A liquid fuel ignition apparatus having a liquid fuel reservoir, means including a wick, an air pump and a porous filter for turning a portion of liquid fuel into bubbles, and a high voltage generator for applying a high voltage across a pair of discharge electrodes disposed in close proximity to the bubbling portion of the liquid fuel so as to ignite the liquid fuel bubbles by spark discharge occurring across the discharge electrodes.

6 Claims, 12 Drawing Figures iiiiiiiiliin. v

PATENTED W5 3. 7 59 .658

sum 2 or 7 FIG.2

PATENTED SEPI 81973 SHEH 5 If 7 FIG.9

PAIENTED SEP! 8 I975 SHEH 8 0f 7 mOk. NON MON fin mm .wz. m2.

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1 LIQUID FUEL IGNITION APPARATUS This invention relates to apparatus for igniting liquid fuel such as kerosene or gasoline.

Liquid fuel such as kerosene or gasoline is generally difficult to ignite compared with gaseous fuel. In an attempt to overcome this difficulty, a system has'been recently developed and put in practical use in a combustion apparatus such as a kerosene stove using liquid fuel. According to this system, liquid fuel under pressure is ejected from a nozzle in an atomized form and a spark produced due to spark discharge is applied to the atomized fuel to ignite same. However, the combustion apparatus employing this system is disadvantageous in that it requires a nozzle for atomizing the liquid fuel and means for applying pressure to the liquid fuel for successfully ejecting the liquid fuel from the nozzle. The apparatus of this kind is further disadvantageous inthat it is difiicult to obtain a uniform fuel-air mixture to be ejected from the nozzle and the ignition rate of the fuel-air mixture is quite low especially when a spark is applied thereto by a high voltage generator employing a piezo-electric element. It is therefore an object of the present invention to provide a novel liquid fuel ignition apparatus which is free from defects as above described and can reliably ignite liquid fuel in spite of a simple construction.

, Another object of the present invention is to provide a liquid fuel ignition apparatus in which liquid fuel is turned into bubbles and a spark generated by means such as a high voltage generator is applied thereto for igniting the liquid fuel.

' .The above and other objects, features and advantages of the present invention will be apparent from the a following description of p'erferred embodiments thereof taken in conjunction with the accompanying drawings, in which: 1

, FIG. 1 is a schematic front elevational view partly in section of an embodiment of the present invention;

FIG. 2 is a schematic front elevational view partly in section of another embodiment of the present invention;

FIG. 3 is a schematic front elevational view partly in section of a further embodiment of the present invention;

FIG. 4 is a schematic front elevational view partly in section of a still further embodiment of the present invention;

FIG. 5 is a schematic front elevational view partly in section of a yet further embodiment of the present invention;

FIG. 6 is a schematic front elevational view partly in section of another embodiment of the present invention;

FIG. 7 is a schematic front elevational view partly in section showing a partial modification of the apparatus shown in FIG-6;

FIG. 8 is a schematic front elevational view partly in section of still another embodiment of the present invention;

FIG. 9 is a schematic front elevational view partly in section showing a partial modification of the apparatus shown in FIG. 8;

FIG. 10 is a schematic front elevational view partly in section of yet another embodiment of the presentinvention;

FIG. 11 l is a plan view of parts of the apparatus shown in FIG. 10; and

FIG. 12 is a schematic front elevational view partly in section of another embodiment of the present invention.

Referring first to FIG. 1, a fuel reservoir 1 contains a quantity of liquid fuel 2 such as petroleum or kerosene therein. A tubular member 3 extends through the upper wall of the fuel reservoir 1 and is provided with a reduced-diameter lower end portion 4 which is immersed in the liquid fuel 2, A wick 5 is contained in the tubular member 3 and its lower end portion extends through the reduced-diameter lower end portion 4 of the tubular member 3 to be immersed in the liquid fuel 2. A porous filter 6 of sintered porous glass, sintered porous metal, glass fibers, asbestos fibers, sponge or the like is securely fitted in the upper end opening of the tubular member 3. An air supply pipe 7 is inserted at one end portion thereof into the tubular member 3, and a piston is slidably received in the other end portion of the air supply pipe 7. The piston 8 is provided with a valve member 9 as shown, and a rod 10 is connected at one endto the piston 3. A high voltage generator 11 employing a piezo-electric element is actuated in response to the manipulation of an actuating shaft 12 on which an actuating arm 13 is fixedly mounted for unitary rotation therewith. A lever 14 is pivoted at one end to the arm 13 by a pivot pin 15 and at the other end to the rod 10 by a pivot pin 16. A pair of discharge electrodes l7 and Marc disposed opposite to each other above the porous filter 6 and are electrically connected to the high voltage generator lll by respective high voltage leads 19 and 20.

The upper end portion of the wick 5 disposed in the tubular member 3 is in contact with the lower surface of the porous filter 6 so that the porous filter 6' is gradually impregnated with the liquid fuel 2 sucked up by the Wick 5. The portion of the air supply pipe 7 lying within the tubular member 3 is bent in the form of L so that air supplied through the pipe 7 can be effectively fed to pass through the porous filter 6. The high voltage generator ill is so constructed that a high voltage is generated thereby when the actuating shaft 12 is rotated in a direction of the arrow a'through a predetermined angle.

In operation, rotation of the actuating shaft 12 in the direction of the arrow a causes rotation of the arm 13 fixedly mounted on the actuating shaft 112 in the same direction, and the piston 8 connected to the arm 13 by the lever 14 and rod 10 moves in a direction of the arrow 0. As a result, the valve member 9 is urged to its closed position and air within the .air supply pipe 7 is forced intothe tubular member Eito be supplied to the porous filter 6. Due to the passage of air through the porous filter 6, a multiplicity of tiny bubbles in the form of vesicles of the liquid fuel filled with air are produced on the upper surface of the porous filter 6. Further rotation of the actuating shaft 12 in the direction of the arrow a causes generation of a high voltage by thehigh voltage generator 11 and spark discharge occurs across the discharge electrodes 17 and 158. The spark thus produced igtites the bubbles so that. combustion of the liqopposite direction or direction of the arrow d. The valve member 9 is urged to its open position due to the above movement of the piston 8 so that external air is drawn into the air supply pipe 7 to prepare for subsequent ignition.

The purpose of the provision of the reduceddiameter portion 4 at the lower end portion of the tubular member 3 is to ensure effective supply of air fed into the air supply pipe 7 to the porous filter 6. This reduced-diameter portion 4 is unnecessary when the air supply pipe 7 is arranged so that its upper end is in direct contact with the lower surface of the-porous filter 6. In the embodiment described above, the piston 8 is mounted directly in the air supply pipe 7 to constitute an air pump, but an air pump may be separately prepared and connected to the air supply pipe 7.

It will be understood from the above description that the present invention provides a liquid fuel ignition apparatus which comprises a porous filter impregnated with liquid fuel, a high voltage generator employing a piezo-electric element, an air pump arranged for interlocking operation with actuating means for the high voltage generator for supplying air to the porous filter thereby producing bubbles of the liquid fuel filled with air on the upper surface of the porous filter, and a pair of discharge electrodes connected to the high voltage generator and disposed in close proximity to the bubbles for producing spark discharge thereby igniting the liquid fuel. According to the present invention, bubbles of liquid fuel are produced and a spark is applied to the bubbles to ignite the liquid fuel. This arrangement is advantageous over the prior art apparatus in that a large-sized pump is not required and a unifonn mixing ratio between the liquid fuel and air can be obtained which leads to a remarkably improved ignition rate. According to the present invention, further, the pump for supplying air to the porous filter is arranged for interlocking operation with the actuating means for the high voltage generator. This arrangement is advantageous in that the liquid fuel can be successfully ignited by mere manipulation of the actuating shaft and thus the apparatus can be very simply handled.

In the arrangement above described, the size of the pores of the porous filter 6' is an important matter in order that the liquid fuel can be reliably ignited. More precisely, when the pores have a very small diameter, the amount of air supplied through the pores is quite small relative to the amount of liquid fuel impregnated in the porous filter resulting in insufficient formation of bubbles, and the liquid fuel existing in an excessive amount due to too minute bubbles cannot be satisfactorily ignited with a spark produced by the discharge electrodes connected to the high voltage generator 11. Further, the manufacture of the porous filter having very minute pores is disadvantageous in respect of costs.

On the other hand, when the pores of the porous filter 6 have a very large diameter, the amount of air supplied through the pores is excessively large compared with the amount of liquid fuel sucked up by the capillary action and the bubbles thus produced are destroyed almost instantaneously resulting in the impossibility to ignite the liquid fuel.

From the above viewpoint, the inventors have made a series of experiments and experimentally determined that the size of the pores of the porous filter 6 should preferably lie in the range of 0.5 to 100 microns. The

ignition cannot be satisfactorily attained when the size of the pores is outside of the range above specified.

It will be understood that the present invention employs a porous filter having a multiplicity of pores of the size lying in the range of 0.5 to microns, and liquid fuel is turned into the form of bubbles by this porous filter so that it can be satisfactorily ignited by a spark produced in close proximity to the bubbles. The present invention is advantageous over the prior art apparatus in which liquid fuel is atomized for ignition in that the mixing ratio between liquid fuel and air is remarkably uniform and the ignition rate can thereby be remarkably improved. The present invention which requires solely the bubbling of liquid fuel is advantageous over the prior art apparatus of the kind described in that a pump having a high compression rate is unnecessary and its overall construction can be very simplified.

Referring to FIG. 2 showing another embodiment of the present invention, a fuel reservoir 101 contains a quantity of liquid fuel 102 such as petroleum or kerosene therein. A tubular member 103 is provided with a reduced-diameter lower end portion 104 which is immersed in the liquid fuel 102. A porous filter 105 of sintered porous metal, sintered porous glass, glass fibers, asbestos fibers, sponge or the likeis securely fitted in the upper end opening of the tubular member 103. A wick 106 is contained in the tubular member 103 in such a manner that its upper end portion is in contact with the lower surface of the porous filter 105 and its lower end portion extends through the reduceddiameter lower end portion 104 of the tubular member 103 to be immersed in the liquid fuel 102. An air supply pipe 107 is connected to an intermediate portion of the tubular member 103, and a cylinder 108 integral with the air supply pipe 107 extends upwardly to constitute an air pump in conjunction with a piston 109 slidably received therein. The piston 109 is provided with a valve member 110 as shown, and a rod 111 is connected at one end to the piston 109. A high voltage generator 1 12 employing a piezo-electric element is actuated in response to the manipulation of an actuating shaft 113. An actuating arm 114 is fixedly mounted on the actuating shaft 113, and a manipulating lug 115 extends from a portion of the outer periphery of the actuating arm 114. A lever 116 is pivoted at one end to the other end of the rod 11 1 and at the other end to a portion of the outer periphery of the actuating arm 114. A pair of discharge electrodes 117 and 118 are disposed opposite to each other above the porous filter 105 and are electrically connected to the high voltage generator 112 by respective leads 119 and 120. The upper end portion of the wick 106 is in contact with the lower surface of the porous filter 105 so that the porous filter 105 is gradually impregnated with the liquid fuel 102 sucked up by the wick 106 due to the capillary action.

In operation, rotation of the actuating shaft 113 in a direction of the arrow a causes sliding movement of the piston 109 in a direction of the arrow b due to the fact that the piston 109 is connected to the actuating shaft 113 through the rod 111, lever 116 and actuating arm 114. As a result, the valve member 110 is urged to its closed position and air within the cylinder 108 is forced into the tubular member 103 through the air supply pipe 107. Due to the fact that the tubular member 103 is provided with the reduced-diameter lower end portion 104, air forced into the tubular member 103 is effectively supplied to the porous filter 105. Due to the supply of air to the porous filter 105, a multiplicity of tiny bubbles in the form of vesicles of the liquid fuel filled with air are produced on the upper surface of the porous filter 105. Further rotation of the actuating shaft 113 through a predetermined angle in the direction of the arrow at causes generation of a high voltage by the high voltage generator 112. As a result, a spark is produced across the discharge electrodes 117 and 118 to ignite the bubbles of the liquid fuel formed on the upper surface of the porous filter 105. Since the mixing ratio between the liquid fuel and air in the bubbles is substantially uniform, ignition can be attained at a very satisfactory rate.

It will be understood from the above description that the present invention provides a liquid fuel ignition apparatus which comprises a tubular member having a reduced-diameter lower end portion and containing therein a wick which is immersed in liquid fuel at its lower end portion, a porous filter securely fitted in the 2 upper end opening of the tubular member and in contact with the upper end portion of the wick at its lower surface, a high voltage generator employing a piezoelectric element, a pair of discharge electrodes connected to the high voltage generator and disposed above the porous filter, and an air pump'arranged for interlocking operation with actuating means for the high voltage generator for supplying air under pressure into the tubular member for producing bubblesof the liquid fuel on the upper surface of the porous filter so that a spark produced across the discharge electrodes disposed above the porous filter is applied to the bubbles to ignite the liquid fuel. According to the present invention, the tubular member is provided with the reduced-diameter lower end portion and the air pump is arranged for interlocking operation with the actuating means for the high voltage generator for supplying air under pressure into the tubular member. This arrangement is advantageous in that air can be satisfactorily supplied to the porous filte'r to produce the bubbles by merely operating the air pump. The present invention is further advantageous in that its overall construction can be remarkably simplified due to the fact that the tubular member, the air supply pipe and the cylinder can be formed as an integral unit. According to the present invention, the air pump for supplying air under pressure to the porous filter-for producing the bubbles of liquid fuel on the upper surface of the porous filter is arranged for interlocking operation with the actuating means for the high voltage. generator employing the piezo-electric element. This arrangement is advantageousin that the actuation of the high voltage generator can automatically produce the bubbles of liquid fuel and the liquid fuel can be very easily ignited.

Referring to F 10. 3 showing a further embodiment of the present invention, a fuel reservoir 201 contains a quantity of liquid fuel 202 such as petroleum or kerosene therein. A tubular member 203 has a generally U- shaped portion 205 which is immersed in the liquid fuel 202and is provided with a perforation 200 for the suction of the liquid fuel. One end portion 206 of the tubular member 203 is shaped in the form of a cylinder to accommodate a wick 207 therein. A porous filter 208 of sintered porous metal, sintered porous glass, glass fibers, asbestos fibers, sponge or the like is securely fitted in the upper end opening of the wick accommodatelectric element is actuated in response to the manipulation of an actuating shaft 218. An actuating arm 219 is fixedly mounted on the actuating shaft 210, and a manipulating lug 220 extends from a portion of the outer periphery of the actuating arm 219. A lever 221 of the actuating arm 219. A pair of discharge electrodes 200 and 210 are disposed opposite to each other above the porous filter 200 and are electrically connected to the high voltage generator 215 by respective leads 210 and 217.

The high voltage generator 215 is so constructed that rotation of the actuating shaft 210 in a direction of the arrow at through a predetermined angle causes generation of a high voltage by the high voltage generator 215 due to the fact that the piezo-electric element is de formed by a force imparted by a hammer (not shown). In operation, rotation of the actuating shaft 210 in the direction of the arrow a causes sliding movement of the piston212 in a direction of thearrow b since the piston 212 is connected to the actuating shaft 210 through the rod 214, lever 2 21 and actuating arm 219. As a result, the valve member 213 is urged to its closed position and airwithin the cylinder 211 is fed toward the wick accomoodating portion 200 through the U-shaped poring portion 206. The other end portion 21 1 of the tubular member 203 is also shaped in the form of a cylinder tion205, And, at the same time, the liquid fuel 202 is drawn into the tubular'member 203 through the liquid fuel intake perforation 204 to be fed into the wick accommodating portion 206. As a result, the liquid fuel 202 is absorbed by the wick 207 accommodated in the wick accommodating portion 206 and the porous filter 200 is impregnated with the liquid fuel 202. Further supply of air under pressure into the wick accommodating portion 206 from the cylinder 211 produces a multiplicity of tiny bubbles in the form of vesicles of the liquid fuel filled with air on the upper surface of the porous filter 208. After the bubbles have been produced on the upper surface of the porous filter 200 by the ma nipulation of the actuating shaft 210 in the manner above described, the actuating shaft 210 is further rotated in the direction of the arrow a until finally a high voltage is generated by the high voltage generator 215. Due to the application of the high voltage, a spark is produced across the discharge electrodes 209 and 210 to ignite the bubbles of the liquid fuel filled with air.

lt will be understood from the above description that the present invention provides a liquid fuel ignition apparatus which comprises a tubular member which is immersed in liquid fuel at its U-shaped portion having a liquid fuel intake perforation, a porous filter securely fitted in one end of the tubular member, a high voltage generator employing a piezo-electric element, an air pump mounted at the other end of the tubular member and arranged for interlocking operation with actuating means for the high voltage generator for supplying air under pressure into the tubular member so as to force air through the porous filter impregnated with the liquid fuel drawn through the liquid fuel intake perforation thereby to produce bubbles of the liquid fuel on the upper surface of the porous filter, and a pair of discharge electrodes connected to the high voltage generator and disposed above the porous filter in close proximity to the latter so that the bubbles can be ignited by a spark produced across the discharge electrodes in response to the application of the high voltage from the high voltage generator. The present invention in which liquid fuel is turned into bubbles and a spark is applied to such bubbles to ignite same is advantageous over the prior art apparatus adapted for atomizing the liquid fuel in that a very satisfactory ignition rate can be obtained and the ignition can be reliably attained. According to the present invention, the liquid fuel intake perforation is provided at the U-shaped portion of the tubular member which is immersed in the liquid fuel and air is fed from one end of the tubular member toward the other end thereof. This arrangement is advantageous over the prior art arrangement in that a wick of large length is unnecessary and the overall construction can be remarkably simplified. Further, according to the present invention, the air pump for supplying air under pressure into the tubular member for producing the bubbles of the liquid fuel on the upper surface of the porous filter is arranged for interlocking operation with the actuating means for the high voltage generator employing the piezo-electric element. This arrangement is advantageous in that the actuation of the high voltage generator can automatically produce the bubbles of the liquid fuel and thus the liquid fuel can be very easily ignited.

Referring to FIG. 4 showing a still further embodiment of the present invention, a fuel reservoir 301 contains a quantity of liquid fuel 302 such as petroleum or kerosene therein. A tubular member 303 is immersed at its lower end portion in the liquid fuel 302 and accommodates therein a wick 304 whose lower end portion is also immersed in the liquid fuel 302. A generally L-shaped air supply pipe 305 extends into the tubular member 303 so that one end thereof is disposed in the upper end opening of the tubular member 303. A porous filter 306 of sintered porous metal, sintered porous glass, glass fibers, asbestos fibers, sponge or the like is securely fitted in this end opening of the air supply pipe 305. A piston 307 is slidably received in the other end portion of the air supply pipe 305 and is provided with a valve member 308 as shown. A rod 309 is connected at one end to the piston 307. A high voltage generator 310 employing a piezo-electric element is actuated in response to the manipulation of an actuating shaft 311. An actuating arm 312 is fixedly mounted on the actuating shaft 311, and a manipulating lug 313 ex tends from a portion of the outer periphery of the actuating arm 312. A lever 314 is pivoted at one end to the other end of the rod 309 and at the other end to a portion of the outer periphery of the actuating arm 312. A pair of discharge electrodes 315 and 316 are disposed opposite to each other above the porous filter 306 and are electrically connected to the high voltage generator 310 by respective leads 317 and 318. The upper end portion of the wick 304 is in contact with the outer peripheral surface of the porous filter 306 and extends slightly upwardly beyond the upper end of the tubular member 303. Due to the fact that the outer peripheral surface of the porous filter 306 is engaged by the upper end portion of the wick 304, the liquid fuel 302 is sucked up by the wick 304 due to the capillary action so that the porous filter-306 is gradually impregnated with the liquid fuel 302 from its outer peripheral surface portion.

In operation, rotation of the actuating shaft 311 in a direction of the arrow a causes rotation of the actuating arm 312 in the direction of the arrow a, hence sliding movement of the piston 307 in a direction of the arrow b. As a result, the valve member 308 is urged to, its closed position and air within the air supply pipe 305 is supplied to the porous filter 306 to pass through the porous filter 306 to be discharged outwardly. Due to the passage of air through the porous filter 306, a multiplicity of tiny bubbles in the form of vesicles of the liquid fuel filled with air are produced on the upper surface of the porous filter 306. Further rotation of the actuating shaft 311 through a predetermined angle in the direction of the arrow a causes generation of a high voltage by the high voltage generator 310 since the piezo-electric element is deformed by a force imparted by a hammer (not shown). Spark discharge occurs across the discharge electrodes 315 and 316 with the result that the tiny bubbles of the liquid fuel produced on the upper surface of the porous filter 306 are ignited to ignite the liquid fuel impregnated in the wick 304. The actuating shaft 311 for the high voltage generator 310 is engaged by a return spring for automatically restoring the actuating shaft 311 to the original position. Thus, release of the manipulating force imparted to the actuating shaft 311 after the ignition of the liquid fuel causes rotation of the actuating shaft 311 in a direction opposite to the direction of the arrow a to restore the piston 307 to the original position.

It will be understood from the above description that the present invention provides a liquid fuel ignition apparatus which comprises a porous filter securely fitted in the upper end opening of an air supply pipe and engaging the upper end portion of a wick, a high voltage generator employing a piezo-electric element, an air pump operatively connected to an actuating shaft for the high voltage generator for feeding air under pressure into the air supply pipe to produce bubbles of liquid fuel on the upper surface of the porous filter, and a pair of discharge electrodes disposed in close proximity to the porous filter and electrically connected to the high voltage generator. The present invention in which the actuating means for the high voltage generator is operatively connected to the air pump is advantageous in that the actuation of the high voltage generator can automatically produce bubbles of liquid fuel and can automatically ignite the liquid fuel. According to the present invention, arrangement is made so as to turn the liquid fuel into bubbles to ignite the liquid fuel in the form of the bubbles. This arrangement is advantageous over the prior art arrangement adapted for atomizing the liquid fuel in that a large-sized pump is unnecessary and the ignition rate can be remarkably improved in spite of a simple construction.

Referring to FIG. 5 showing a yet further embodiment of the present invention, a fuel reservoir 401 contains a quantity of liquid fuel 402 such as petroleum or kerosene therein. A tubular member 403 is provided with a reduced-diameter lower end portion 404 which is immersed in the liquid fuel 402 contained in the fuel reservoir 401. A small air intake perforation 405 is provided at such a position of the reduced-diameter lower end portion 404 which is above the liquid fuel level. A valve member 406 such as a ball is disposed in the tubular member 403 so that it acts to close the upper end of the reduced-diameter lower end portion 404 in response to an increase in theair pressure within the tu- 9 bular member 403. A porous filter 407 of sintered porous metal, sintered porous glass, glass fibers, asbestos fibers, sponge or the like is securely fitted in the upper end opening of the tubular member 403, and a wick 408 is inserted in the tubular member 403 in such a manner that its upper end portion is in contact with the lower surface of the porous filter 407. A pipe 409 extends laterally from an intermediate portion of the tu- 10 ha] position. Thus, in the subsequent igniting operation, the actuating shaft 414 may merely be rotated in the direction opposite to the direction of the arrow a bular member 403, and a cylinder 410 extends upwardly from the pipe 409 as shown. A piston 411 is slidably received in the cylinder 410, and a rod 412 is connected at one end to the piston 411. A high voltage generator 413 employing a piezo-electric element is actuated in response to the manipulation of an actuating shaft 414. An actuating arm 415 is fixedly mounted on the actuating shaft 414, and a manipulating lug 416 extends from a portion of the outer periphery of the actuating' arm 415.A lever 41 7 is pivoted at one end to the other end of the rod 412 and at the'other end to a portion of the outer periphery of the actuating arm 4151A pair of discharge electrodes 418 and 419 are disposed opposite to each other above the porous filter 407 and are electrically connectedto the high voltage generator 413 by respective leads 420 and 421.

In'operation, rotation of theactuating shaft 414 for actuating the high voltage generator 413 a direction of the arrow a causes sliding movement of the piston 411 in a direction of the arrow b with the result that the air pressure in the'tubular member 403 is reduced and the ball 406 makes upward movement in a direction of the arrow 0. Air is drawn into the tubular member 403 through the air intake perforation 405, and the liquid fuel 402 is drawn into the tubular member 403 through the reduced-diameter lower end portion 404. Therefore, the wick 408 and the porous filter 407 are successively impregnated with the liquid fuel 402.

When new the actuating shaft 414 for the high voltage generator 413 is rotated in a direction opposite to the direction of the arrow a from the above state, the piston 411 makes sliding movement in a direction opposite to the direction of the arrow b with the result that the air pressure in the tubular member 403 is increased and the'valve member 406 is urged toward the upper end of the reduced-diameter lower end portion 404 of the tubular member 403 to close this opening. Due to the increase in the air pressure within the tubular member 403, air is forced through the porous filter 407 to be discharged outwardly and a multiplicity of tiny bubbles in the form of vesicles of the liquid fuel filled with air are produced on the upper surface of the porous filter 407. Further rotation of the actuating tion of the arrow a and then rotated in the direction opposite to the direction of the arrow a. However, generally, the high voltage generator 413 isso arranged that the actuating shaft 414 is rotated in the direction opposite to the direction of the arrow 4 and then rotated in the direction of the arrow a to be restored to the origibecause the bubbles of the liquid fuel sucked up in the preceding igniting operation are already produced on the upper surface of the porous filter 407.

It will be understood from the above description that the present invention provides a liquid fuel ignition apparatus which comprises a tubular member provided with a reduced-diameter lower end portion which is normally immersed in liquid fuel, a small air intake perforation provided at such a position of the reduceddiarneter lower end portion which is above the liquid fuel level, a porous filter mounted in the upper end opening of the tubular member, a wick contained in the tubular member and in contact at its upper end portion with the lower surface of the porous filter, a valve member such as a ball for closing the upper end of the reduced-diameter lower end portion of the tubular member in response to an increase in the air pressure within the tubular member, a high voltage generator employing a piezo-electric element, a piston arranged for interlocking operation "with actuating means for the high voltage generator, said piston being operative to reduce the air pressure "within the tubular member thereby drawing the liquid fuel into the tubular member together with air inhaled through the air intake perforation so as to impregnate the porous filter with the liquid fuel and tofproduce bubbles of the. liquid fuel on the upper surface of the porous filter, and a pair of discharge electrodesdisposed above the porous filter and electrically connected to the high voltage generator to be applied with a high voltage thereacross from the high voltage generator, so as to ignite the bubbles by a spark produced across thereacross. The arrangement in which the liquid fuel is turned into bubbles and a spark is applied to the bubbles to ignite same is advantageousin that a very satisfactory ignition rate can be obtained. According to the presentinvention, the reduceddiameter lower end portion of the tubular member is provided with an air intake perforation and a valve member is disposed in the tubular member for closing the upper end of the reduced-diameter lower end portion of the tubular member so that these means act as an air supply pump. The present invention having such means is advantageous in that the piston arranged for interlocking operation with the actuating means for the high voltage generator can singly effectively feed. air and liquid fuel into the tubular member'for producing bubbles on the upper surface of the porous filter, and the overall construction can thereby be remarkably simplified. According to the present invention, the piston for increasing and decreasing the air pressure within the tubular member is arranged for interlocking operation with the actuating means for the high voltage generator which applies a high voltage across'the discharge electrodes disposed above the porous filter. This arrangement provides a further advantage in that, in response to the actuation of the high voltage generator, bubbles of the liquid fuel are produced on the. upper surface of the porous filter to be ignited by a spark produced across the discharge electrodes.

Referring to FIG. 6 showing another embodiment of the present invention, a fuel reservoir 501 contains a quantity of liquid fuel such as petroleum or kerosene therein. A tubular member 503 having a closed bottom is immersedat its lower end portion in the liquid' fuel 502. A tubular extension 504 extends laterally from a portion adjacent to the lower end of the tubular member 503, and a normally open valve member 505 is provided in the tubular extension 504 adjacent to the end which is closed except a small opening. A wick 506 is accommodated in the tubular member 503, and a porous filter 507 of sintered porous metal, sintered porous glass, glass fibers, asbestos fibers, sponge or the like is securely fitted in the upper end opening of the tubular member 503. A wire-gauze cap 508 is mounted on the upper end of the tubular member 503 so as to cover the porous filter 507. An air supply pipe 509 is connected to an intermediate portion of the tubular member 503, and a cylinder 510 extends upwardly from the air supply pipe 509 so as to constitute an air pump in conjunction with a piston 511 slidably received therein. The piston 511 is provided with an air valve member 512 as shown, and a rod 513 is connected at one end to the piston 511. A high voltage generator 514 employing a piezo-electric element is actuated in response to the manipulation of an actuating shaft 515. An actuating arm 516 is fixedly mounted on the actuatingshaft 515 and a manipulating lug 517 extends from'a portion of the outer periphery of the actuating arm'516. A lever 518 is pivoted at one end to the 7 may be employed in lieu thereof for producing spark discharge thereacross.

It will be understood from the above description that the present invention provides a liquid fuel ignition apparatus which comprises a tubular member which has a closed bottom and is immersed in liquid fuel at its lower end portion, a normally open valve member mounted in a submerged extension of the tubular memactuating means for the high voltage generator for forcother end of the rod 513 and at the other end to a portion of the outer periphery of the actuating arm 516. A discharge electrode 519 is disposed in close proximity to the porous filter 507, and the discharge electrode 519 and the wire-gauze cap 508 are electrically connected to the high voltage gen ra r 514 by respective leads 520=and 521.

The interior of the lower end portion of the tubular member 503 is filled with the liquid fuel 52 sin the valve member 505 in the tubular extension 504 extending laterally from the tubular member 503 is normally open. Therefore, the lower end portion of the wick 506 is immersed in the liquid fuel 502 and the porous filter 507 is impregnated with the liquid fuel 502 which is sucked up by the wick 506. In operation, rotation of the actuating shaft 515 for actuating the high voltage generator 514 in a direction of the arrow :1 causes sliding movement of the piston 511 in a direction of the arrow b with the result that the valve member 512 is urged to its closed position and air within the cylinder 510 is forced into the tubular member 503 through the air supply pipe 509. Consequently, the valve member 505 is urged to its closed position and air under pressure is forced through the porous filter 507 to be discharged into the atmosphere. Due to the passage of air through the porous filter 507 which is impregnated with the liquid fuel 502, a multiplicity of tiny bubbles in the form of vesicles of the liquid fuel filled with air are produced on the upper surface of the porous filter 507. Further rotation of the actuating shaft 515 in the direction of the arrow 0 in FIG. 6 causes generation of a high voltage by the high voltage generator 514 since the piezoelectric element is deformed by a force imparted by a hammer (not shown). This high voltage is applied across the discharge electrode 519 and the wire-gauze cap 508 to produce a spark thereacross so that the bubbles of the liquid fuel existing on the upper surface of the porous filter 507 is ignited by the spark. Although the embodiment shown in FIG. 6 employs the discharge electrode 519 and the wire-gauze cap 508 for the purpose of producing spark discharge thereacross, a pair of discharge electrodes 522 and 523 as shown in FIG.

ing air under pressure into the tubular member through an air supply pipe, and a set of discharge electrodes disposed in close proximity to the porous filter for producing spark discharge thereacross in response to the application of a high voltage from the high voltage generator. According to the present invention, air is forcedly fed through the tubular member into the porous filter to turn the liquid fuel impregnated in the porous filter into bubbles and a spark occurring across the discharge electrodes is utilized to ignite the bubbles. This arrangement is advantageous in that a difficultly ignitable liquid fuel can easily be ignited at a remarkably satisfactory ignition rate. According to the present invention, further, the air pump for forcedly feeding air under pressure into the tubular member accommodating the wick therein is arranged for interlocking operation with the actuating means for the high voltage generator employing the piezo-electric element. This arrangement is advantageous in that single manipulation of the actuating means can sequentially carry out the formation of the bubbles on the upper surface of the porous filter and the application of the spark to the bubbles thus produced. Further. although the tubular member 503 mounting the porous filter 507 in the upper end opening thereof is illustrated as a single pipe, this tubular member 503 may be divided into an upper portion mounting the porous filter 507 and a lower portion immersed in the liquid fuel 502 and these portions may be connected together by a tube.

Referring to FIG. 8 showing still another embodiment of the present invention a fuel reservoir 601 contains a quantity of liquid fuel 602 such as petroleum or kerosene therein. A tubular member 603 of metal material is securely fixed to a base 621 by a fitting 622 and is provided with a reduced-diameter lower end portion 604 which is immersed in the liquid fuel 602. A wick 605 is accommodated in the tubular member 603 and extends at its lower end portion into the liquid fuel 602. A porous filter 606 of sintered porous metal, sintered porous glass, glass fibers, asbestos fibers, sponge or the like is securely fitted in the upper end opening of the tubular member 603. A generally L-shaped air supply pipe 607 extends at one end portion thereof into the tubular member 603, and a piston 608 is slidably received in the other end portion of the air supply pipe 607. The piston 608 is provided with a valve member 609 as shown, and a rod 610 is connected at one end to the piston 608. A high voltage generator 611 employing a piezo-electric element is mounted on the base 621 and is actuated in response to the manipulation of an actuating shaft 612 on which an actuating arm 613 is fixedly mounted. A lever 614 is pivoted at one end to the other end of the rod 610 by a pivot pin 616 and at the other end to the arm 613 by a pivot pin 615. A discharge electrode 617 is fixed to .the upper end of the tubular member 603, while another discharge electrode 618 is disposed opposite to the discharge electrode 617 at a position above the porous filter 606. A high voltage lead 619 connects electrically the discharge electrode 618 to the high voltage generator 611. On the other hand, the discharge electrode 617 is electrically connected to the high voltage generator 611 through the tubular member 603,- fitting 622 and base 621. The

upper end portion of the wick 605 is in contact with the lower surface of the porous filter 606 so that the porous voltage generator 611 is so constructed that rotation of I the actuating shaft 612 through a predetermined angle in a direction'of the arrow a causes generation of a high voltage.

In operation, rotation of the actuating shaft 612 in the direction of the arrow a causes rotation'of the arm 613 in the same direction, hence sliding movement of the piston 608 in a direction of the arrow 0. As a result, the valve mem ber 609 is urged to'its closed position and air within the air supply pipe 607 is forced into the tubular member 603 to pass through the porous filter 606 so thata multiplicityof tiny bubbles in the form of vesicles of the liquid fuel filled with air are produced on the upper surface of the porous filter 606. Further rotation of the actuating shaft 612 in the direction of the arrow a from this state causes generation of a high voltage by the high voltage generator 611 and spark discharge occurs across the discharge electrodes 617and 618. The spark ignites the bubbles of the liquid fuel to burn the liquid fuel impregnated in the porous filter 606. After the igniting operation, the actuating shaft 612 is rotated in a direction of the arrow b to cause slid-- ing movement of the piston 608 in the direction of the arrow d. This urges. the valve member 609 to its open position so that air is drawn into the air supply pipe 607 to prepare for subsequent ignition.

The purpose of the provision of the reduceddiameter portion'604 at the lower end portion of the tubular member 603 is to ensure that air under pressure forced into the tubular member 603 be effectively supplied to the porous filter 606. This reduced-diameter lower end portion 60 1 need not be provided when the air supply pipe-607 is soarranged that the upper end thereof is in direct contact with the lower surface of the porous filter 606. Further, although the piston 608 is directly mounted in the air supply pipe 607 in the present embodiment to constitute an air pump, an air pump may be separately provided and connected to the air supply pipe 607. Furthermore, the above description has referred to an arrangement in'which-the discharge electrode 617 is mounted directly on the upper end of the tubular member 603, but a wire-gauze cap 623 may bemountejd on the upper end of the tubular member 603 as shownin FIG. 9 so that it replacesthe discharge electrode.

it will be understood from the above description that the present invention provides a liquid fuel ignition ap' n paratus which comprises a tubular member accommodating a wick therein and fixed to a base by a fitting, a

. porous filter securely fitted in the upper end opening of and a set of discharge electrodes disposed in close I proximity to the porous filter to be applied thereacross a high voltage generated by the high voltage generator through the base, the fitting, the tubular member and a lead so that a spark produced across the discharge electrodes ignites the bubbles of the liquid fuel. The present invention in which the liquid fuel is turned into bubbles and a spark is applied to the bubbles to ignite same is advantageous over the prior art apparatus in thata large-sized pump is unnecessary and a remarkably satisfactory ignition rate can be obtained due to the fact that the liquid fuel and air are mixed together at a uniform ratio. According to the present invention, the pumpfor feeding air under pressure to the porous filter is arranged for interlocking operationwith the actuating means for the high voltage generator. This arrangement is advantageous in that mere manipulation of .the actuating means can cause ignition of the liquid fuel in a very simple manner. According to the present invention, further, one of the discharge electrodes is electrically connected to the high voltage generator through the base mounting the high voltage generator thereon. This arrangement provides a very simple over all structure in that a single high voltage lead is only required to connect the other discharge electrode to the high voltage generator.

Referring'to FIGS. 10 and 11 showing yet another embodiment of the present invention, a fuel reservoir 701 contains a quantity of liquid fuel 702 such as petroleum or kerosene therein. A tubular member 703 extends through the upper wall of the fuel reservoir 701 and is immersed at its lower end portion in the liquid fuel 702. A wick 704 is accommodated in the tubular member 703 and extends at its lower end portion into the liquid fuel 702. A generally L-shaped air supply pipe 705 extends at one end portion thereof into the tubular member 703, and a piston 707 is slidably received in the other end portion of the air supply pipe 705. A porous filter 706 of sintered porous metal, sintered porous glass, glass fibers, asbestos fibers, sponge or the like is securely fitted in the upper end opening of the air supply pipe 705. A rod 709 is connected at one-end to the piston 707, and the piston 707 is provided with a valve member 708 as shown. A high voltage generator 710 employing a piezo-electric element is actuated in response to the manipulation of an actuating shaft 711. An actuating arm 712 is fixedly mounted on the actuating shaft 711 and a manipulating lug 713 extends from a portion of the outer periphery of the actuating arm 712. A lever 716 is pivoted at one end to the other end ,of the rod 709 and at the other end to a portion of the outer periphery of the actuating arm 712. A discharge electrode 715 is mounted on the upper end of the tubular member 703 and is electrically connected to the high voltage generator 710. Another discharge electrode .716 is disposed opposite to the discharge electrode 716 and is electrically connected to the high voltage generator 710 by a high voltage lead 717. A shutter 718 extends at one end portion thereof into the tubular member 703 through a slot 719 provided adjacent to the upper end of the tubular member 703. A swinging lever 720 is pivoted at the central portion thereof to a stationary member by a pivot pin 721 and is provided with a pair of spaced longitudinal slots 724 and 724 adjacent to the opposite ends thereof. A pin 722 provided at the other end of the shutter 718 is received in the slot 724, while a pin 723 provided at an intermediate portion of the rod 709 is received in the slot .725. The wick 704 is immersed at its lower end portion in the liquid fuel 702 and is in contact at its upper end portion with the outer peripheral surface of the porous filter 706 fixed in the upper end opening of the air supply pipe 705 so that the porous filter 706 is impregnated with the liquid fuel 702 sucked up by the wick 704 due to the capillary action. Normally, the actuating shaft 712 for the high voltage generator 710 is maintained at an angular position in which it is rotated clockwise to its movable limit, and the shutter 718 is in a fully advanced position closing the upper end opening of the tubular member 703.

In operation, the actuating shaft 711 is rotated counter-clockwise to actuate the high voltage generator 710. The rotation of the actuating shaft 711 in the counter-clockwise direction causes-rotation of the ac-' tuating arm 712 in the same direction so that the piston 707 connected to the actuating arm 712 by the rod 709 moves leftward in FIG. 10. Therefore, the swinging lever 720 makes swinging movement about the pin 721 to cause retracting movement of the shutter 718. The valve member 708 on the piston 707 is urged to its closed position and air within the air supply pipe 705 is forcedly passed through the porous filter 706 to be discharged into the atmosphere so that a multiplicity of tiny bubbles in the form of vesicles of the liquid fuel filled with air are produced on the upper surface of the porous filter 706.

When the actuating shaft 711 is rotated further counter-clockwise until finally the high voltage generator 710 is actuated, a high voltage is applied across the discharge electrodes 715 and 716 to produce a spark thereacross and the bubbles are ignited by this spark. The burning flame ignites the liquid fuel impregnated in the wick- 704 and the liquid fuel continues to burn.

Rotation of the actuating shaft 711 clockwise causes sliding movement of the piston 707 rightward in FIG. 10, hence swinging movement of the swinging lever 720 in the counter-clockwise direction. As a result, the shutter 718 is advanced to close the upper end opening of the tubular member 703 and the liquid fuel ceases to burn. The valve member 708 on the piston 707 is urged to its open position again and air is drawn into the air supply pipe 705 to prepare for subsequent ignition.

It will be understood from the above description that the present invention provides a liquid fuel ignition apparatus which comprises a tubular member accommodating therein a wick which is immersed at its lower end portion in liquid fuel and in contact at its upper end portion with a porous filter, .a high voltage generator employing a piezo-electric element, an air pump arranged for interlocking operation with actuating means for the high voltage generator for forcedly feeding air under pressure through the porous filter thereby producing bubbles of the liquid fuel on the upper surface of the porous filter, a shutter arranged for interlocking operation with the actuating means for the high voltage generator for openably closing the upper end opening of the tubular member, and a set of discharge electrodes electrically connected to the high voltage generator for producing a spark thereacross in response to the application of a high voltage from the high voltage generator thereby igniting the bubbles, the shutter being retracted in response to the deenergization of the high voltage generator to cease the combustion of the liquid fuel. According to the present invention, the air pump for forcedly feeding air under pressure through the porous filter for producing bubbles of the liquid fuel on the upper surface of the porous filter and the shutter openably closing the upper end opening of the tubular member are arranged for interlocking operation with the actuating means for the high voltage generator employing the piezo-electric element. This arrangement is advantageous in that the formation of the bubbles of the liquid fuel and the ignition of the bubbles as well as the extinction of the burning flame can be completely carried out in response to the manipulation of the actuating means for the high voltage generator. The present invention in which the liquid fuel is turned into bubbles and a spark is applied to the bubbles to ignite same is advantageous in that a difficulty ignitable liquid fuel can be very easily ignited due to the fact that the liquid fuel forming the bubbles is in a filmy state and a uniform mixture of the liquid fuel and air can thereby be obtained.

Referring to FIG. 12 showing another embodiment of the present invention, a fuel reservoir 801 contsins a quantity of liquid fuel 802 such as petroleum or kerosene therein. A tubular member 803 is provided with a reduced-diameter lower end portion 804 which is immersed in the liquid fuel 802. A porous filter 805 of sintered porous metal, sintered porous glass, glass fibers, asbestos fibers, sponge or the like is securely fitted in the upper end opening of the tubular member 803. The tubular member 803 accommodates therein a wick 806 which is in contact at its upper end portion with the lower surface of the porous filter 805 and extends at its lower end portion into the liquid fuel 802. An air supply pipe 807 extends laterally from a portion adjacent to the upper end of the tubular member 803, and a cylinder 808 slidably receiving therein a piston 809 is connected integrally with the air supply pipe 807 for constituting an air pump. The piston 809 is provided with a valve member 810 as shown, and a rod 811 is connected at one end to the piston 809. A high voltage generator 812 employing a piezo-electric element is actuated in response to the manipulation of an actuating shaft 813. An actuating arm 814 is fixedly mounted on the actuating shaft 813, and a manipulating lug 815 extends from a portion of the outer periphery of the actuating arm 814. A lever 816 is pivoted at one end to the other end of the rod 811 and at the other end to a portion of the outer periphery of the actuating arm 814. A pair of discharge electrodes 817 and 818 are disposed opposite to each other above the porous filter 805 and are electrically connected to the high voltage generator 812 by respective leads 819 and820. Another tubular member 821 is disposed in parallel with the tubular member 803 in suitably spaced relation from the latter and accommodates therein a wick 822 which is immersed at its lower end portion in the liquid fuel 802. The upper end of the wick 822 terminates adjacent to the upper end of the tubular member 803. Due to the fact that the upper end portion of the wick 806 is in contact with the lower surface of the porous filter 805,

. the porous filter 805 is gradually impregnated with the liquid fuel 802 sucked up by thecapillary action of the wick 806 accommodated in the tubular member 803.

In operation, the actuating shaft 813 is rotated in a direction of the arrow to actuate the high voltage generator 812. The rotation of the actuating shaft 813 in this direction causes sliding movement of the piston 809 ha direction of the arrow b since the piston 809. is connected to the actuating shaft 813 by the rod 811, lever 816 and actuating arm 814. As a result, the valve member 810 is urged to its closed position and air within the cylinder 808 is forced through the air supply pipe 807 into the tubular member 803. Air under pressure thus fed into the tubular member 803 can be effectively supplied to the porous filter 805 because the tubular member 803 is provided with the reduceddiameter portion 804 at its lower end portion. Thus, a multiplicity of bubbles in the form of vesicles of the liquid fuel filled with air are produced on the upper surface of the porous filter 805. Further rotation of the actuating shaft 813 through a predetermined angle causes generation of a high voltage by the high voltage generator 812 and this high voltage is applied across the discharge electrodes 817 and 818 so that a spark is produced thereacross to ignite the bubbles of the liquid fuel formed on the upper surface of the porous filter 805. The ignition can be attained at a very satisfactory rate since the ratio of the liquid fuel to air in the bubbles is substantially uniform. The flame produced due to the combustion of the liquid fuel bubbles ignites'the liquid fuel impregnated in the adjoining wick 822, and the liquid fuel sucked up by the capillary action of the wick 822 continues to burn even if the combustion of the liquid fuel bubbles ceases in a very short period of time. This wick 822 may be the main or auxiliary or pilot wick of the kerosene stove. I

It will be understood from the above description that the present invention provides a liquid fuel ignition apparatus which comprises a tubular member provided with a reduced-diameter lower end portion and accommodating therein a wick which is immersed at its lower end portion in liquid fuel and is in contact at its upper end portion with the lower surface of a porous filter securely fitted in the upper endopening of the tubular member, a high voltage generator employing a piezoelectric element, a pairof discharge electrodes disposed above the porous filter and electrically connected to the high voltage generator, an air pump arranged for interlocking operation with actuating means for the high voltage generator for forcedly feeding air under pressure into the tubular member thereby producing bubbles of the liquid fuel on the upper surface of the porous filter so that the bubbles can be ignited by a spark produced across the discharge electrodes, and another tubular member disposed in parallel with the first-mentioned tubular member in suitably spaced relation from the latter and accommodating therein an that air can be supplied to the porous filter by merely feeding air into the tubular member by the air pump which is arranged for interlocking operation with the actuating means for the high voltage generator. Further, the apparatus has a very simple construction due to the fact that the tubular member, the air supply pipe and the cylinder are formed as a unit. Furthermore, the arrangement in which the air pump for forcedly passing air through the porous filter for producing the bubbles of the liquid fuel on the upper surface of the porous filter is arranged for interlocking operation with the actuating means for the high voltage generator employing the piezo-electric element is advantageous in that, in response to the manipulation of the actuating means for energizing the high voltage generator, the liquid fuel bubbles can be automatically produced to be ignited by the spark and the flame thus produced, even if it lasts for a very short period of time, is utilized to ignite the liquid fuel impregnated in another wick for the continuous combustion.

What is claimed is:

1. A liquid fuel ignition apparatus comprising a reservoir containing liquid fuel therein, means for producing bubbles in the liquid fuel using a porous filter having pores of sizes ranging from 0.5 to microns, and a high voltage generator for applying a high voltage across a pair of discharge electrodes positioned adjacent the bubble forming area of the porous filter, whereby the liquid fuel in the form of vesicles is ignited by spark discharge occurring across said discharge electrodes under high voltage applied thereto from said high voltage generator.

2. A liquid fuel ignition apparatus as claimed in claim 1, in which said porous filter is securely fitted in the upper end opening of a hollow body the other end of which is submergible in said liquid fuel, a valve member which is normally open and is urged to its closed position in response to supply of air into said hollow body is mounted in the submerged portion of said hollow body, and an air supply pipe is connected to said hollow body for. supplying air under pressure into said hollow body thereby producing the bubbles of the liquid fuel.

3. A liquid fuel ignition apparatus as claimed in claim 1, in which said bubble producing means comprises a porous filter in contact with the upper end portion of a wick sucking up the liquid fuel, and a pump for supplying air under pressure to said porous filter.

4. A liquid fuel ignition apparatus as claimed in claim 1, in which said high voltage generator comprises a piezo-electric element, and means for imparting deformation to said piezo-electric element so that said piezoelectric element is subjected to deformation in response to the formation of the bubbles of the liquid fuel thereby to generate a high voltage for producing spark discharge across said discharge electrode means.

8. A liquid fuel ignition apparatus as claimed in claim 0, in which one of elements forming said means for imparting deformation to said piezo-electric element is associated with a piston of a pump supplying air under pressure to a porous filter.

6. A liquid fuel ignition apparatus as claimed in claim 1, in which said discharge electrode means comprises a pair of electrodes which are disposed opposite to each other above the bubbling portion of the liquid fuel produced by said bubble producing means.

i t h. ,8 k 

1. A liquid fuel ignition apparatus comprising a reservoir containing liquid fuel therein, means for producing bubbles in the liquid fuel using a porous filter having pores of sizes ranging from 0.5 to 100 microns, and a high voltage generator for applying a high voltage across a pair of discharge electrodes positioned adjacent the bubble forming area of the porous filter, whereby the liquid fuel in the form of vesicles is ignited by spark discharge occurring across said discharge electrodes under high voltage applied thereto from said high voltage generator.
 2. A liquid fuel ignition apparatus as claimed in claim 1, in which said porous filter is securely fitted in the upper end opening of a hollow body the other end of which is submergible in said liquid fuel, a valve member which is normally open and is urged to its closed position in response to supply of air into said hollow body is mounted in the submerged portion of said hollow body, and an air supply pipe is connected to said hollow body for supplying air under pressure into said hollow body thereby proDucing the bubbles of the liquid fuel.
 3. A liquid fuel ignition apparatus as claimed in claim 1, in which said bubble producing means comprises a porous filter in contact with the upper end portion of a wick sucking up the liquid fuel, and a pump for supplying air under pressure to said porous filter.
 4. A liquid fuel ignition apparatus as claimed in claim 1, in which said high voltage generator comprises a piezo-electric element, and means for imparting deformation to said piezo-electric element so that said piezo-electric element is subjected to deformation in response to the formation of the bubbles of the liquid fuel thereby to generate a high voltage for producing spark discharge across said discharge electrode means.
 5. A liquid fuel ignition apparatus as claimed in claim 4, in which one of elements forming said means for imparting deformation to said piezo-electric element is associated with a piston of a pump supplying air under pressure to a porous filter.
 6. A liquid fuel ignition apparatus as claimed in claim 1, in which said discharge electrode means comprises a pair of electrodes which are disposed opposite to each other above the bubbling portion of the liquid fuel produced by said bubble producing means. 